asp.net - Filter IList<T> -

list<paymenttype> paymentoptions = _paymentmethods; 

_paymentmethods public property , i'd filter copy of , store in variable paymentoptions

list<int32> noinvoice = new list<int32>(){ 16, 4 , 6 }; foreach (paymenttype pt in paymentoptions) {     if(noinvoice.contains(pt.id))     {         paymentoptions.remove(pt);         break;     } } 

but if run second time, variable _paymentmethods not contain removed item anymore.

it seems go reference instead of value... prefer not copy list array should use linq or there other way?

edit: have now:

list<paymenttype> paymentoptions = shopcontroller.currentshop.paymentmethods; list<paymenttype> paymentoptionsfiltered = new list<paymenttype>();      if (havetofilter) {     list<int32> noinvoice = new list<int32>() { 16, 4, 6 };      foreach (paymenttype pt in paymentoptions)     {         if (!noinvoice.contains(pt.id))         {             paymentoptionsfiltered.add(pt);         }     }     repeaterpaymentoptions.datasource = paymentoptionsfiltered; } else {     repeaterpaymentoptions.datasource = paymentoptions; } 

use linq:

list<paymenttype> paymentoptionswithnoinvoice =   paymentoptions.where(a=> !noinvoice.contains(a.id)).tolist();